This is why I say, go SHIELD. SHIELD is close enough to superheroic that it wouldn't feel out of place, while also not requiring a narrow focus or an all-in bet on a singular character. Also, since the concept doesn't require any specific character, it gives them a lot more freedom in how they write it ( ie, freedom to kill off cast members ).

Would you recast Nick Fury and Maria Hill, or would you cut them completely out of the show and just reference them? It's hard for me to imagine a SHIELD show without showing SHIELD's director or its second-in-command. I would at least need the Helicarrier to feature prominently.